shell 循环语句

1、while

2、for

3、until

4、select

while

#!/bin/bash

# 显示一系列数字

count=1

while [ $count -le 6 ]; do
    echo $count
    count=$((count + 1))
done
echo "finished"

　　

for

输出3次uptime

#!/bin/bash  

for i in 1 2 3 4 5
do
    echo "$i-->$(uptime)"
done

　　

批量解压缩当前文件夹下所有的.tar.gz 文件

#!/bin/bash  

for i in `ls ./*.tar.gz`
do
     tar -zxvf $i >/dev/null
done

　　

求1~100 的和

#!/bin/bash  

#注意变量赋值的时候,=两边绝对不能有空格
sum=0
for (( i=1; i<=100; i++ ))
do
   sum=$(( $sum + $i ))
done  

echo "1+2+3+...+100=$sum"

　　

until

#!/bin/bash
a=0
until [ $a -gt 10 ]
do
    echo $a
    a=`expr $a + 1`
done

　　

select

#!/bin/bash

echo "What is your favourite OS?"
select var in "Linux" "Gnu Hurd" "Free BSD" "Other"; do
  break;
done
echo "You have selected $var"
该脚本的运行结果如下：

What is your favourite OS?
1) Linux
2) Gnu Hurd
3) Free BSD
4) Other
#? 1
You have selected Linux